I can't help with Kiwi4 but I've played around with quite a few ODB2 bluetooth devices in the past including the Kiwi3.
The gotcha with the Kiwi3 is that it used "low energy bluetooth" which isn't compatible with everything (which is why some of the other threads talk about working on this device but not that). Seems someone in their wisdom took a working bluetooth spec and split it into a few different versions that don't work with each other.
Cheap ebay Chinese ODB-II devices are hit and miss and I've had a really good one that worked till it randomly stopped.
Don't know where on the planet you are but in AU/NZ the Jaycar ones work well on everything I've tried them on without lag. https://www.jaycar.com.au/obd-ii-engine-code-reader-with-bluetooth-technology/p/PP2145
...and they have a good return policy if for some reason it doesn't work on your setup. They also sell a wireless one that I've not tried but it might suit your setup better if you are using a external GPS or another device on bluetooth at hte same time.
A bit off topic but Race Chrono is a killer app for ODB-II bluetooth. Race track video with odb-ii data overlay, lots of tracks in there or you can mark-out your own. You will get best results using a higher frequency external GPS (10hz) as phones typically use a 1Hz GPS.